It will be noted that, in the remainder of the description, the term videophone system will be used to mean both a conventional videophone system in which two terminals may exchange audio-visual data and a videoconferencing system where more than two terminals are involved in a call.
Videophone systems are already known, for example that described in patent document FR-A-2 673 060. This type of system generally consists of a terminal equipped with a communications interface linked to a telephone or other line, a camera and a restoration unit with a screen on which the image of the speaker positioned in front of the camera and the remote speaker can be displayed.
One of the present curbs on the important development of videophone systems is the cost of the terminal which is exacerbated primarily by the price of the restoration unit, which is generally equipped with a liquid crystal display screen.
However, most homes are equipped with a television receiver that is generally colour. This type of equipment has become commonplace and is a standard consumer item sold at a relatively affordable price. Some homes even have several television receivers for convenience.
It is found nowadays that watching television programmes, either by cable or radio, private or public, is not the only focus of interest of this equipment and other uses have been developed and will continue to do so. In fact, with the TV peripheral unit socket, the television screen can be used to display pictures from different sources, such as video recorders, optical video disc readers, portable video cameras, such as the Camescope.RTM.. In this respect, one can also include the use by the young (and not so young as well) of interactive video games.
The television receiver is thus becoming a tool that is used as a monitor with a screen and loudspeaker, independently of its VHF or UHF modulator and is thus put to a different use from that for which it was designed.
It is based on these facts that the applicant has developed an audio-visual telecommunications unit enabling use of a television set display screen. The great majority of homes now own such a system, and the cost of the display screen thus becomes marginal in the cost of the videophone system.
It will be noted that, in this description, the audio-visual telecommunications equipment involved operates in real time.
The purpose of the invention is thus to provide such an audio-visual telecommunications unit that operates in real time and is structured in such a way that, firstly, all the functions available on the videophone system are accessible by the remote control generally provided with television sets or by means of the control component of the telephone module of the videophone system, such as the keypad of a telephone handset, for example, and, secondly, these functions are displayed on screen without disrupting normal operation of the set.
An audio-visual telecommunications unit is also known, in particular from patent document JP-A-4 236 472, of a type comprising a videophone terminal designed for connection to a telecommunication network, an image processing unit, also termed an output controller, designed firstly to receive audio-visual signals emitted by the said videophone terminal and, secondly, to process the said signals in order to be able to compose a picture with sounds, in accordance with various proposed methods and to transmit signals representing the said composite picture to the restoration unit on a television set.